JPH0812686A - Production of arylphosphoric ester - Google Patents

Abstract

PURPOSE:To obtain the subject compound useful as a flame-retardant having improved separation of oil from water in a purifying process by synthesizing an arylphosphoric ester from a phosphorus oxyhalide and a phenol, adding an active hydrogen-containing compound such as an amine and continuing the reaction. CONSTITUTION:An arylphosphoric ester is synthesized by dehydrohalogenating a phosphorus oxyhalide (e.g. phosphorus oxychloride) with a corresponding monohydric phenol and/or a polyhydric phenol, and is expressed by formula I [(n) is 0-20; R<1> to R<4> are each (hydroxy)phenyl or a 1-3C alkyl-substituted aryl; R<5> is a group of formula II (X is methyl or a halogen) or a group of formula III ((l) and (m) are 0-4; A is a group of formula IV, etc.)]. The arylphosphoric ester is continuously reacted with an active hydrogen-containing compound selected from amines of [preferably a compound of formula V (R<6> and R<7> are each a 1-8C alkyl and the sum of carbon atoms of both the groups is >=4)] and/or alcohols to give the objective compound.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a phosphoric acid ester mainly used as a flame retardant. More specifically,
The present invention relates to a method for inexpensively producing a high-quality aryl phosphate ester with a small residual halogen content, using phosphorus oxyhalide and monohydric phenols and / or polyhydric phenols as main raw materials.

[0002]

2. Description of the Related Art As a method of imparting flame retardancy to a resin, a method of adding a flame retardant such as an inorganic hydroxide, an organic halide or a phosphoric acid ester is widely used. Of these, phosphoric acid esters are highly effective non-halogen flame retardants,
In particular, it is widely used for resins containing oxygen atoms in the molecule. Triphenyl phosphate (TPP) is well known as a representative phosphoric acid ester flame retardant. TPP is usually synthesized by the dehydrochlorination reaction of phosphorus oxychloride and phenol, and the unreacted substances are removed and purified through distillation and recrystallization. However, TPP has a drawback that it volatilizes at a low temperature, for example, and therefore volatilizes during the process of mixing with a resin and molding, causing problems such as contamination of the work environment, mold deposit, and exudation on the surface of a molded product. . As a phosphoric acid ester compound for solving these problems, Japanese Patent Publication No.
19858, Japanese Patent Publication No. 53-44340, Japanese Patent Publication No. 62
No. 25706, Japanese Patent Publication No. 2-18336, JP-A-55
There are compounds of the general formula (1) described in No. 118957.

[0003]

Embedded image

In order to improve the physical properties of the resin composition, for example,
JP-A-5-148403 and JP-A-5-209086 propose a hydroxyl group-containing aryl phosphate ester. These phosphoric acid esters are synthesized by a method of dehydrohalogenating a phosphorus oxyhalide with corresponding monohydric phenols and / or polyhydric phenols using a metal halide such as AlCl ₃ or MgCl ₂ as a catalyst. For details, refer to JP-A-50-101489 and JP-B-5.
4-32818, JP-B-62-25706, JP-A-63-227632, JP-A-1-223158 and the like.

In the phosphoric acid ester synthesized by these methods, halogen elements generally remain in an amount of 0.1 to 1 wt%. The halogen element is hydrogen halide dissolved in the product, a material derived from the metal halide of the catalyst used, and a material due to unreacted halogen bonded to phosphorus such as diarylphosphoric halide. It is not practical to react at a high temperature for a long time in order to eliminate a compound having an unreacted halogen that is bonded to phosphorus, because it causes an increase in manufacturing cost and thermal transformation of the product.

When these halogen-containing compounds are mixed in, problems such as coloring of the resin composition and mold corrosion during extrusion / molding occur. Therefore, a purification step is generally provided, and washing with water and / or alkaline water is adopted. However, the compound having unreacted halogen that binds to phosphorus is hydrolyzed to diaryl phosphate or the like, and this acts as a surfactant, so that an emulsion is easily formed, and it is extremely difficult to separate the oil phase product and the aqueous phase. Not only that, but the recovery rate of the product will be significantly worse. or,
Due to the poor oil phase separation property, the residual halogen concentration in the product becomes high, and problems such as coloring of the resin composition and mold corrosion during extrusion / molding are likely to occur.

[0007]

SUMMARY OF THE INVENTION The present invention is directed to the completion of the dehydrohalogenation reaction under mild conditions to eliminate unreacted halogens bound to phosphorus, thereby providing a high quality aryl having a low residual halogen content. It is an object to provide a method for producing a phosphoric acid ester at low cost.

[0008]

Means for Solving the Problems As a result of intensive studies aimed at achieving the above object, the present inventors have found that after the phosphoric acid ester synthesis reaction, a compound having highly reactive active hydrogen is added to continue the reaction. Then, it was found that the dehydrohalogenation reaction can be easily completed, and a high quality phosphoric acid ester having a small residual halogen content can be easily obtained, and the present invention has been completed.

That is, according to the present invention, when an aryl phosphoric acid ester is produced, the phosphoric acid ester is synthesized by dehydrohalogenation reaction of phosphorus oxyhalide with corresponding monohydric phenols and / or polyhydric phenols. A compound having an active hydrogen selected from amines, amines and / or alcohols, further continuing the reaction, and replacing the unreacted halogen bonded to phosphorus with a hydrophobic substituent. In the production method, preferably, the phosphoric acid ester is represented by the general formula (1)

[0010]

[Chemical 4]

A compound represented by the formula (1), wherein the compound having active hydrogen is R ⁶ NHR ⁷ [wherein R ⁶ and R ⁷ are independently an alkyl group having 1 to 8 carbon atoms, and the sum of both carbon atoms is 4 or more], the amount of the compound having active hydrogen used is 0.1 mol% or more based on the charged phosphorus oxyhalide, and the reaction temperature is the ester synthesis reaction temperature and the active hydrogen. It is a method for producing a phosphoric acid ester having a lower temperature than the lower boiling point of the compound.

The present invention will be described in detail below. The production method of the present invention, in the first stage, with phosphorus oxyhalogen chloride,
A compound having a highly reactive active hydrogen selected from amines and / or alcohols in the latter stage after synthesizing an aryl phosphate ester by a dehydrohalogenation reaction of a corresponding monohydric phenol and / or polyhydric phenol Is added to continue the reaction to complete the dehydrohalogenation reaction.

Examples of the monohydric phenols used here include phenol, cresol, xylenol, trimethylphenol, ethylphenol, methyl-ethylphenol, diethylphenol, propylphenol, isopropylphenol, methyl-propylphenol, ethyl-propylphenol. , Dipropylphenol and the like. Also, as polyhydric phenols,
For example, hydroquinone, resorcin, bisphenol A,
Examples thereof include bisphenol S, 1,1-bis (4-hydroxyphenyl) ethane, tetrabromobisphenol A, tetrabromobisphenol S, pyrogallol and phloroglucin.

A known method can be used for synthesizing the aryl phosphate ester in the first stage of the production method. For example, JP-A-50-101489 discloses a method of dehydrochlorinating a phenylphosphonic dichloride or phenylphosphorochloride and a corresponding dihydric phenol, and JP-B-54-32818 discloses a method using a Lewis acid as a catalyst. A method for dehydrochlorinating phosphorus oxychloride and the corresponding monohydric phenol and dihydric phenol is disclosed in JP-A-63-22763.
No. 2 uses phosphorus chloride or magnesium chloride as a catalyst to dehydrochlorinate the corresponding divalent phenol with phosphorus oxychloride, then removes unreacted phosphorus oxychloride and further removes the corresponding monovalent phenol. A method of reacting with hydrochloric acid is described. In the phosphoric acid ester thus obtained, the hydrogen halide and the compound having the unreacted halogen bonded to the catalyst and phosphorus remain after the unreacted material is removed by distillation under reduced pressure. The amount of residual halogen content varies depending on the synthesis conditions, but is generally in the range of 0.1 to 1 wt%.

In the latter step, a compound having active hydrogen selected from amines and / or alcohols is added to a compound having an unreacted halogen bonded to phosphorus, and the reaction is further continued to complete the dehydrohalogenation reaction. In this case, the halogen atom is replaced with a hydrophobic substituent. Among the compounds having active hydrogen used here, amines are represented by the general formula (2)

[0016]

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[In the formula, R ⁶ and R ⁷ are independently hydrogen, an alkyl group having 1 to 20 carbon atoms, an alkenyl group, a cycloalkyl group or an arylalkyl group, but both are not hydrogen. . ], A typical compound is n
-Butylamine, isobutylamine, t-butylamine, n-pentylamine, neopentylamine, hexylamine, cyclohexylamine, heptylamine, octylamine, 2-ethylhexylamine, decylamine, laurylamine, cetylamine, stearylamine, oleylamine, benzylamine , Diethylamine, dipropylamine, diisopropylamine, methyl-n-butylamine, di-n-butylamine, di-isobutylamine, di-n-pentylamine, di-n-hexylamine, methylcyclohexylamine, cyclohexylbenzylamine, dicyclohexyl Amine, di-2
-Ethylhexylamine, didecylamine, dilaurylamine, dicetylamine, dioleylamine, dibenzylamine and the like.

Alcohols have the general formula

[0019]

[Chemical 6]

[In the formula, R ⁸ is an alkyl group having 1 to 20 carbon atoms, an alkenyl group, a cycloalkyl group or an arylalkyl group. ], As a typical compound,
Methanol, ethanol, propanol, isopropanol, allyl alcohol, n-butyl alcohol, isobutyl alcohol, t-butyl alcohol, n-pentyl alcohol, neopentyl alcohol, n-hexyl alcohol, cyclohexyl alcohol, heptyl alcohol, octyl alcohol, 2-ethylhexyl Examples thereof include alcohol, nonyl alcohol, decyl alcohol, lauryl alcohol, oleyl alcohol and benzyl alcohol.

Of these, the general formula (2)

[0022]

[Chemical 7]

[Wherein R ⁶ and R ⁷ are independently an alkyl group, an alkenyl group or a cycloalkyl group having 1 to 8 carbon atoms, and the sum of the carbon atoms of both is 4 or more. ] Indicated by 2
Primary amines are particularly desirable. As a specific compound,
For example, dipropylamine, diisopropylamine, methyl-n-butylamine, di-n-butylamine, di-
Isobutylamine, di-n-pentylamine, di-n-
Hexylamine, methyl-cyclohexylamine, di-
2-ethylhexylamine and the like can be mentioned.

These compounds having active hydrogen may be used alone or in combination. Further, a non-aqueous solvent may be used in combination for facilitating the mixing of these compound additives and the phosphoric acid ester. The addition amount of the compound having active hydrogen varies depending on the synthesis reaction conditions of the phosphoric acid ester, but is suitably 0.1 mol% or more and equimolar or less with respect to the phosphorus oxyhalide as the raw material. If it is 0.1 mol% or less, a sufficient effect cannot be obtained, and even if it is added in an equimolar amount or more, the improvement effect is small and an excessive amount of the additive remains unreacted. However, when the compound also serves as a solvent for lowering the viscosity of the phosphoric acid ester composition, an equimolar amount or more can be added.

The temperature at which the compound acts depends on the kind of the compound, but is preferably lower than the lower temperature of the ester synthesis reaction temperature and the boiling point of the compound having active hydrogen.
Due to the action of the compound having active hydrogen, the unreacted halogen remaining in the esterification reaction step is replaced with a hydrophobic substituent according to the following reaction.

[0026]

Embedded image

[0027]

[Chemical 9]

[Where X represents a halogen element. ]

[0029]

EXAMPLES The present invention will be specifically described below with reference to examples, examples and comparative examples.

[0030]

Reference Example 1 Synthesis of phosphoric acid ester. 114 g of bisphenol A, 157 g of phosphorus oxychloride, and 3 g of anhydrous magnesium chloride were charged into a 500 ml four-necked flask equipped with a stirrer / reflux tube and placed under a nitrogen stream 1
The reaction was carried out at 00 to 140 ° C. Hydrogen chloride gas generated during the reaction was collected with water, and the progress of the reaction was monitored by the amount of the generated hydrogen chloride gas. After completion of the reaction, while maintaining the reaction temperature, the pressure of the flask was reduced to 200 mmHg or less by a vacuum pump, and unreacted phosphorus oxychloride was collected by a trap. Then, the flask was cooled to room temperature, 188 g of phenol was added, and the mixture was heated to 140 to 180 ° C. for reaction. Hydrogen chloride gas generated during the reaction was collected with water, and the progress of the reaction was monitored by the amount of the generated hydrogen chloride gas. After completion of the reaction, while maintaining the reaction temperature, the pressure of the flask was reduced to 200 mmHg or less by a vacuum pump, and unreacted phosphorus oxychloride was collected by a trap. Light yellow transparent reactant 304 represented by the following chemical formula
g was obtained.

[0031]

[Chemical 10]

The chlorine content measured by ion chromatography was 0.
It was 32%.

[0033]

Reference Example 2 By the same method as in Reference Example 1 except that 55 g of resorcinol was used instead of 114 g of bisphenol A, 276 g of a pale yellow and transparent reaction product represented by the following chemical formula was obtained.

[0034]

[Chemical 11]

The chlorine content measured by ion chromatography was 0.
It was 41%.

[0036]

Reference Example 3 By the same method as in Reference Example 1, except that 125 g of bisphenol S was used instead of 114 g of bisphenol A, 307 g of a pale yellow and transparent reaction product represented by the following chemical formula was obtained.

[0037]

[Chemical 12]

The chlorine content measured by ion chromatography was 0.
It was 37%.

[0039]

Reference Example 4 326 g of a colorless and transparent reaction product represented by the following chemical formula was prepared in the same manner as in Reference Example 1 except that 216 g of cresol was used instead of 188 g of phenol.
I got

[0040]

[Chemical 13]

The chlorine content measured by the ion chromatography method is 0.
It was 28%.

[0042]

Example 1 70 g of the phosphoric acid ester obtained in Reference Example 1 was placed in a 300 ml tall beaker, 7 g of 2-ethylhexylamine was added, and the mixture was kept at 100 ° C. for 1 hour while stirring. 100 ml of warm water was added to this composition, and the mixture was vigorously stirred at 60 ° C. for 5 minutes and then allowed to stand to separate an aqueous phase. Next, 100 ml of 0.1 N sodium hydroxide aqueous solution was added and the same washing was performed twice, and 100 ml of warm water was further added and the same washing was performed twice. In each case, the ester phase and the aqueous phase separated within 5 minutes. Water and excess amine were removed by vacuum drying to obtain 69 g of a pale yellow transparent viscous composition. The residual chlorine concentration of the composition was 0.5 ppm or less.

[0043]

Example 2 57 g of the phosphoric acid ester obtained in Reference Example 2 was placed in a 300 ml tall beaker and isopropanol 1 was added.
g was added and the mixture was maintained at 80 ° C. for 1 hour while stirring. 100 ml of warm water was added to this composition, and the mixture was vigorously stirred at 60 ° C. for 5 minutes and then allowed to stand to separate an aqueous phase. Next, 100 ml of 0.1 N sodium hydroxide aqueous solution was added and the same washing was performed twice, and 100 ml of warm water was further added and the same washing was performed twice. In each case, the ester phase and the aqueous phase separated within 5 minutes. Water and residual alcohol were removed by vacuum drying to obtain 55 g of a pale yellow transparent viscous composition. The residual chlorine concentration of the composition was 0.5 ppm or less.

[0044]

Example 3 73 g of the phosphoric acid ester obtained in Reference Example 3 was placed in a 300 ml tall beaker, 6 g of di (2 ethylhexyl) amine was added, and the mixture was stirred at 150 ° C. for 1 hour.
I kept it for hours. To this composition, add 100 ml of warm water to 60
After vigorous stirring for 5 minutes at 0 ° C., the mixture was allowed to stand and the aqueous phase was separated.
Next, 100 ml of 0.1 N sodium hydroxide aqueous solution was added and the same washing was performed twice, and 100 ml of warm water was further added and the same washing was performed twice. In each case, the ester phase and the aqueous phase separated within 2 minutes. Water and excess amine were removed by vacuum drying to obtain 70 g of a colorless and transparent viscous composition. The residual chlorine concentration of the composition was 0.5 ppm or less.

[0045]

Example 4 76 g of the phosphoric acid ester obtained in Reference Example 4 was placed in a 300 ml tall beaker, and dibutylamine 26 was added.
g was added and the mixture was kept at 100 ° C. for 1 hour while stirring.
100 ml of warm water was added to this composition, and the mixture was vigorously stirred at 60 ° C. for 5 minutes and then allowed to stand to separate an aqueous phase. Next 0.1
100 ml of a normal aqueous sodium hydroxide solution was added and the same washing was performed twice, and 100 ml of warm water was further added and the same washing was performed twice. In each case, the ester phase and the water phase are 2
Separated within minutes. Water and excess amine were removed by vacuum drying to obtain 75 g of a colorless and transparent viscous composition. The residual chlorine concentration of the composition was 0.5 ppm or less.

[0046]

Comparative Example 1 To 57 g of the phosphoric acid ester obtained in Reference Example 2, 100 ml of warm water was added, and the mixture was vigorously stirred at 60 ° C. for 5 minutes and allowed to stand to separate the aqueous phase. This separation took more than 20 minutes. Next, 0.1 normal sodium hydroxide aqueous solution 10
The same washing was carried out twice by adding 0 ml, but in each case, it took 120 minutes or more to separate the aqueous phase, and the emulsion phase remained at the interface. Emulsion phase is removed and warm water 10
The same washing was performed twice by adding 0 ml. Water was removed by vacuum drying to obtain 45 g of a yellow viscous composition. The residual chlorine concentration of the composition was 12 ppm.

[0047]

Comparative Example 2 To 76 g of the phosphoric acid ester obtained in Reference Example 4 was added 100 ml of warm water, and the mixture was vigorously stirred at 60 ° C. for 5 minutes and then left standing for 3 hours to recover 60 ml of an aqueous phase. Next, 100 ml of 0.1 N sodium hydroxide aqueous solution was added and the same washing was performed. As a result, emulsification occurred and the aqueous phase could not be separated. The pale yellow transparent ester phase was recovered by centrifugation at 60 ° C. and 3000 rpm for 1 hour, and water was removed by vacuum drying to obtain 63 g of a viscous composition. The residual chlorine concentration of the composition was 20 ppm.

[0048]

As is apparent from the examples, in producing an aryl phosphoric acid ester, the phosphoric acid ester is prepared by a dehydrohalogenation reaction of a monohydric phenol and / or a polyhydric phenol corresponding to phosphorus oxyhalide. After synthesizing, dehydrohalogenation is carried out by adding a compound having active hydrogen selected from amines and / or alcohols to a compound having an unreacted halogen that partially binds to phosphorus, and continuing the reaction. The reaction can be completed under mild conditions, which can improve the oil-water separability in the purification process by washing the product with water and / or alkaline water, and increase the product recovery rate. It is possible to produce a high-quality aryl phosphate ester having a low residual halogen content.

Claims (4)

[Claims] 1. After synthesizing an aryl phosphoric acid ester by dehydrohalogenation reaction of phosphorus oxyhalide with corresponding monohydric phenols and / or polyhydric phenols,
A process for producing an aryl phosphoric acid ester, which comprises adding a compound having active hydrogen selected from amines and / or alcohols and continuing the reaction. 2. The method for producing an aryl phosphoric acid ester according to claim 1, wherein the aryl phosphoric acid ester is a compound represented by the general formula (1). Embedded image 3. The method for producing an aryl phosphoric acid ester according to claim 1, wherein the compound having active hydrogen is an amine represented by the general formula (2). Embedded image [Here, R ⁶ and R ⁷ are independently an alkyl group having 1 to 8 carbon atoms, and the sum of the carbon numbers of both is 4 or more. ] 4. The use amount of the compound having active hydrogen is 0.1 mol% or more based on the charged phosphorus oxyhalide,
The production of aryl phosphate ester according to claim 1, 2 or 3, wherein the reaction temperature is lower than the lower temperature of the ester synthesis reaction temperature and the boiling point of the compound having active hydrogen. Method.